Field
This document relates to a touch-sensitive panel, and more particularly to an electrostatic capacitive touch sensitive panel, which offers increased touch performance by improving the touch accuracy on the edge regions of a touch-sensitive panel with a narrow bezel.
Related Art
Recently, various input devices such as a keyboard, a mouse, a trackball, a joystick, and a digitizer have been used to configure an interface between users and home appliances or various kinds of information communication equipments. However, such input devices as a keyboard, a mouse, etc require the user to learn to use them and take up space. Therefore, the demand for input devices that are convenient and easy to use and reduce erroneous operations is ever increasing. In response to this demand, the use of a touch screen panel for enabling a user to input information by directly touching the screen with their hand or a pen has been suggested.
Touch-sensitive panels are classified into a resistive type, an electrostatic capacitive type, an electromagnetic type, etc. based on a method for sensing a touched portion. The resistive touch-sensitive panel determines a touched position by a voltage gradient based on changes of resistance in a state that a DC voltage is applied to metal electrodes formed on an upper plate or a lower plate. The electrostatic capacitive touch-sensitive panel senses a touched position based on changes in voltage generated in an upper plate or a lower plate when the user touches an equipotential conductive film formed on the upper or lower plate. The electromagnetic touch-sensitive panel senses a touched portion by reading an LC value induced when an electronic pen touches a conductive film. In addition, an optical touch-sensitive panel, an ultrasonic touch-sensitive panel, etc. are known.
Of these touch-sensitive panels, the electrostatic capacitive touch-sensitive panel is classified into a self-capacitance touch-sensitive panel and a mutual capacitance touch-sensitive panel. In the self-capacitance touch-sensitive panel, a plurality of independent patterns are formed in a touch area, and changes in electrostatic capacitance in the independent patterns are measured to determine the presence or absence of a touch. In the mutual-capacitance touch-sensitive panel, x-axis electrode lines or serials (e.g., touch driving electrode lines or serials) and y-axis electrode lines or serials (e.g., sensing electrode lines or serials) intersect each other to form a matrix in a touch electrode forming area of the touch-sensitive panel, a driving pulse is applied to the X-axis electrode lines, and changes in voltage appearing at sensing nodes defined by the crossing points between the X-axis electrode lines and the Y-axis electrode lines are sensed through the Y-axis electrode lines to determine the presence or absence of a touch.
Hereinafter, a related art electrostatic capacitive touch-sensitive panel will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view of a related art electrostatic capacitive touch-sensitive panel. FIG. 2 is a view conceptually showing sensing nodes formed on the touch-sensitive panel of FIG. 1.
Referring to FIGS. 1 and 2, the electrostatic capacitive touch-sensitive panel comprises a touch electrode forming area TA where touch electrodes are formed, an active area AA corresponding to a data display area of a display device, a routing wire forming area RA where routing wires are formed to send and receive signals to and from the touch electrode forming area AA, and a pad forming area PA where routing pads are formed to connect the routing wires to signal lines of a touch driving circuit.
The touch electrode forming area TA comprises a plurality of first touch electrode lines TS1 to TS5 arranged on a transparent substrate 10 in parallel in a first direction (e.g. x-axis direction), and a plurality of second touch electrode lines RS1 to RS6 arranged in parallel in a second direction (e.g. y-axis direction) so as to cross over the first touch electrode lines TS1 to TS5 with an insulation layer (not shown) interposed between them. Points formed by the intersections of the first and second touch electrode lines TS1 to TS5 and RS1 to RS6 are referred to as sensing nodes n11 to n56. Due to the insulation layer (not shown), the first touch electrode lines TS1 to TS5 and the second touch electrode lines RS1 to RS6 are not in contact with each other at the sensing nodes n11 to n56. As such, when a touch driving voltage is applied to either the first touch electrode lines TS1 to TS5 or the second touch electrode lines RS1 to RS6, mutual capacitance occurs between both of the first touch electrode lines TS1 to TS5 and the second touch electrode lines RS1 to RS6.
The active area lies within the area defined by a line connecting the uppermost sensing nodes n11 to n16, a line connecting the lowermost sensing nodes n51 to n56, a line connecting the leftmost sensing nodes n11 to n51, and a line connecting the rightmost sensing nodes n16 to n56. In the related art touch-sensitive panel, the touch electrode forming area TA is extended so that the sensing nodes n11 to n16, n51 to n56, n11 to n51, and n16 to n56 lie outside the active area AA.
The routing wire forming area RA is disposed outside the touch electrode forming area TA where the first and second touch electrode lines TS1 to TS5 and RS1 to RS6 are formed, and comprises a plurality of first routing wires TW1 to TW5 connected to the plurality of first touch electrode lines TS1 to TS5, respectively, and a plurality of second routing wires RW1 to RW6 connected to the plurality of second touch electrode lines RS1 to RS6, respectively.
The pad forming area PA comprises a plurality of first routing pads TP1 to TP5 connected to the plurality of first routing wires TW1 to TW5, respectively, and a plurality of second routing pads RP1 to RP6 connected to the plurality of second routing wire RW1 to RW6, respectively.
The above-mentioned electrostatic capacitive touch-sensitive panel is a device which detects touch positions by detecting changes in electrostatic capacitances at the sensing nodes n11 to n56 closest to the touch positions when the user touches (approaches; hereinafter, simply referred to as ‘touch’) the touch-sensitive panel with a fingers or a conductive metal such as a stylus pen. As the sensing nodes n11 to n56 are used as a reference to trace touch (or approach) positions, the touch electrode forming area TA is larger in size than the active area AA so that the user can touch any point in the entire active area AA corresponding to the display area of the display device.
For this reason, the related art touch-sensitive panel has a wide bezel area (outside the active area AA) with no screen display, thus failing to cope with the recent demand for a narrow bezel.
With the increasing demand for a touch-sensitive panel with a narrow bezel, attempts are being made to make the active area AA and the touch electrode forming area TA similar in size.
Hereinafter, an electrostatic capacitive touch-sensitive panel complying with the recent demand for a narrow bezel will be described with reference to FIGS. 3 and 4. FIG. 3 is a plan view of a related art electrostatic capacitive touch-sensitive panel for a display device. FIG. 4 is a view conceptually showing sensing nodes formed on the touch-sensitive panel of FIG. 3.
The touch-sensitive panel with a narrow bezel of FIG. 3 is identical to the touch-sensitive panel of FIGS. 1 and 2 except that the boundary of the active area AA lies outside the area formed by connecting the uppermost sensing nodes n11 to n16, the lowermost sensing nodes n51 to n56, the leftmost sensing nodes n11 to n51, and the rightmost sensing nodes n16 to n56, so further explanation will be omitted to avoid redundancy.
However, the touch-sensitive panel with a narrow bezel of FIG. 3 requires a substantial reduction of the distance between the edge of the active area and the edge of the touch electrode forming area TA, and therefore the time constant increases due to the increase in distance between the touch electrodes and the routing wires. Moreover, the extension portions of the touch electrode lines TS1 to TS5 and RS1 to RS6 outside the active area AA are reduced, resulting in low touch accuracy on the edge regions.
Accordingly, the touch-sensitive panel with a narrow bezel also brings up the need to consider measures to improve the touch accuracy on the edge regions.